I never got around to posting on here but I was playing around with this today to see if I could get this to work. I’m not entirely sure it’s possible to do a cloth simulation with this (at least not at the moment).
As close as I got with the cloth sim was having the details panel options for for actor Hidden in Game checked and cast shadows as hidden checked. This would cast the shadows but not have a cloth simulation.
When I checked Simulate Physics I was able to get the objects shadow to react but it was based off the cloth sim. So I’m not entirely sure there isn’t a good answer for this at the moment. Post the link to your AnswerHub post here for reference as well and I’ll assign myself to look into this more next week and see if I can get a more resolute answer. Heck, there may be a request in for this already. I’ll gladly see what I can do though! 
Tim